Behavioral studies have shown similarity of action between benzodiazepines (BDZs) and GABA mimetic drugs, indicating that the pharmacological action of BDZs is mediated through GABAergic synapses. The molecular composition of the GABA receptors was studied biochemically. Two separate binding sites (one for 3H-GABA and one for 3H-diazepam) were isolated by differential solubilization from rat brain homogenates with Triton X-100. Photo labeled benzodiazepine receptors were further purified by preparative SDS gel electrophoresis and reverse phase HPLC. This may represent a useful and rapid technique to obtain BZD receptors in almost pure form. Purification of BZD receptors may help to understand the molecular structure and function of the GABA receptor system.